Method of manufacturing memory matrices

ABSTRACT

A novel memory matrix and method of making same employing a support plate having formed therein recesses for receiving annular cores. The recesses include a group of conductive bars extending in each recess and above the plate surface. A group of circumscribing recesses are then provided, of a depth exceeding the core recesses but less than the plate thickness. Cores are then inserted into the recesses, and all recesses filled with an epoxy resin, up to slightly above the surface of the plate. The insulating surface is then printed with conductors interconnecting the ends of the bars as desired. The remaining metal on the other side of the support plate is then removed so that the circumscribed areas are electrically separated.

United States Patent [72] Inventor Ulrich Emst Enz Emmasingel, Eindhoven, Netherlands [21] Appl. No. 745,579 [22] Filed July 17, 1968 [45] Patented June 22, 1971 (73] Assignee U.S. Philips Corporation New York, NY.

[54] METHOD OF MANUFACTURING MEMORY MATRICES 6 Claims, 4 Drawing Figs.

[52] U.S. Cl 340/174, 29/604 [51] Int. Cl G 1 1c 5/04, G1 1c 5/08, G1 1c 11/06 [50] Field olSearch 340/174; 29/625, 433; 317/101 [56] References Cited UNITED STATES PATENTS 3,071,843 1/1963 Horton 317/101 X 3,158,926 12/1964 Nieter 29/625 3,155,948 11/1964 Stern 340/174 3,317,408 5/1967 Barnes et a1. 340/174 X Primary ExaminerStanley M. Urynowicz, Jr. Attorney-Frank R. Trifari ABSTRACT: A novel memory matrix and method of making same employing a support plate having formed therein recesses for receiving annular cores. The recesses include a group of conductive bars extending in each recess and above the plate surface. A group of circumscribing recesses are then provided, of a depth exceeding the core recesses but less than the plate thickness. Cores are then inserted into the recesses, and all recesses filled with an epoxy resin, up' to slightly above the surface of the plate. The insulating surface is then printed with conductors interconnecting the ends of the bars as desired. The remaining metal on the other side of the support plate is then removed so that the circumscribed areas are electrically separated.

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KHEET 2 UF 2 INVENTOR. ULRICH E. ENZ

b AGENT lMllE'llllllOlD 01F MANUFACTURING MEMORY MATRICES The invention relates to a method of manufacturing a memory matrix comprising ferromagnetic annular cores arranged in recesses of a supporting plate, in which cores conductive bars are formed the ends of which are in contact with surface wirings provided on either face of the supporting plate. Owing 'to the sue of surface wirings, for example, printed wirings, the time-consuming individual insertion of metal wires through the magnet cores may be dispensed with.

In a known memory matrix of the kind set forth an insulating plate having annular recesses is used, each of which recesses receives an annular core. The inside of the recess accommodates two or more axial channels made in the insulating material, which channels are filled in some way or other with metal so that conductive barsare formed to which the surface wirings can be connected. Metal filling of a great number of channels of a diameter of not more than a few tenths of a millimeter can be carried out only with great difficulty so that this method is not very appropriate for the manufacture of matrices having annular cores of not more than one or a few millimeters in diameter.

Metal filling of the channels may be carried out by inserting thin metal bars one'by one into the channels by hand. This is, of course, also a very time-consuming and expensive method.

The object of the invention is to provide a considerably cheaper method. The method in accordance with the invention is characterized in that in a metal plate on one side annular recesses are formed so that each of them can receive one of the ferromagnetic annular cores, while in the space inside the annular cores a group of conductive bars is left.

On the same side of the plate groove-shaped recesses of greater depth than the circular recesses are formed, which grooves define connections between bars of adjacent groups formed by plate portions.

Next, the annular cores are inserted into the annular recesses, and then all recesses are filled out with a cold-setting insulating material so that on said side an insulating layer is formed across the annular cores and the metal plate portions with the exception of the ends of the bars, on which layer printed wiring electrically connecting said ends can be provided.

Subsequently, on the other side of the plate the metal is removed to a depth such that the metal plate portions concerned are electrically separated from each other.

In this method, as will be explained more fully hereinafter, the bars inside the annular cores are formed by working a metal plate, so that no narrow channels need be filled with metal.

A memory matrix according to the invention is characterized in that the surface wiring on one side of the supporting plate is formed by metal plate portionsintegral with the bars, while parts thereof other than the bars extend up to the other side of the plate and form together with the insulating material filling out the spaces between the metal plate portions, the supporting plate and the spaces therein for receiving the annular cores. The surface wiring formed already on one side of the supporting plate by said metal parts eliminates the requirement of subsequent application of a separate printed wiring on said side.

The invention will be described more fully with reference to the drawing, in which FIG. 1 is a plan view of a memory matrix according to the invention, at least part thereof and illustrates a method of manufacturing this memory matrix,

FIG. 2 is a sectional view of part of the device of FIG. 1 in an intermediate stage of tlie manufacture;

FIG. 3 is a sectional view of the same part as that shown in FIG. 2 in the finalstage and FIG. 4 is a perspective view of part of the device of FIG. 1 in the same stage as that shown in FIG. 2.

FIG. II shows part of a memory matrix having a great number of ferromagnetic annular cores 1, four of which are shown in the FIG. in broken'lines for the sake of clarity. The annular cores may be made in known manner of a kind of ferrite having a rectangular hysteresis loop. The cores 1 are supported from a mainly metal plate 2, for example, of copper or aluminum, having on one side annular, preferably circular recesses 3 so that each of them can receive one of the ferromagnetic cores .1 as illustrated, while in the spaces inside the annular cores 1 a group of conductive metal bars 5 (here three) is left (see also FIG. 4, where the annular core 1 is completely omitted for the sake of clarity). On the same side of said metal plate-here on the upper side-groove-shaped recesses 7 of greater depth than the recesses 3 are formed in the metal plate, which first-mentioned recesses 7, as is shown in FIG. I, circumscribe connections between bars 5 of metal parts 9 forming individually two adjacent groups. Since the maximum depth of the recesses 3 and 7 on one side of the metal plate is smaller than the thickness of the metal plate, the latter forms in this stage a coherent unit (see FIG. 2).

After the recesses 3 and 7 and the bars 5 are formed, for example by means of a known photoresist method, the annular cores I are inserted into the circular recesses 3. This may be carried out also in known manner by vibrations, if necessary, in conjunction with suction through openings 11 provided in the metal plate 2. All recesses are then filled out with a curable insulating material for example epoxy resin so that on the upper side of the metal plate an insulating layer covers the annular cores 1 and all metal parts with the exception of the free ends of the bars 5, on which layer a printed wiring 13 electrically connecting these ends can be provided in this stage or in a further stage. A few parts of this printed wiring are indicated by way of example in broken lines in FIG. 1. On the second side, here the lower side, the metal of the metal plate 2 is then removed to a depth such that the circumscribed metal plate parts 9 are electrically separated from each other.

FIG. 3 shows part of the matrix plate in this final stage. It will be obvious that each of the bars 5 together with the metal plate part 9 connected to one of its ends and with the stripshaped metal layer 13 at its other end constitutes a conductor passing through the annular core 1 concerned.

Etching of the metal plate 2 is preferably carried out so that, as is shown in FIG. 2, the bars 5 project slightly above the surface of the further part of the plate. A further possibility of forming the recesses 3, the bars 5 and the grooves 7 in the metal plate 2 consists in compression and extrusion of the metal by means of a stamp having, in effect, the negative of the desired profile of the metal plate. In this method the metal plate consists preferably of aluminum. 0n the lower side of the metal plate 2 the metal may be removed either by etching or by grinding.

FIG. 3 shows that in the ready matrix plate the surface wiring on one side, here on the lower side of the supporting plate, is formed by the metal plate parts 9 integral with the bars 5. The FIG. also shows that not only the bars 5 but also some further parts, for example the part 9 in FIG. 3, extend up to the other side, here the upper side of the plate. The metal plate parts 9, together with the insulating material 15 filling out the spaces between the metal plate parts, form the supporting plate for the matrix and the spaces provided therein for the annular cores 1. From the foregoing it will be obvious that the formation of the conductive bars 5 does not require filling out narrow openings with metal and that there is no need for inserting metal bars one by one into narrow openings.

lclaim:

l. A method of manufacturing a memory matrix having ferromagnetic annular cores arranged in annular recesses of a composite supporting plate including metal plate parts and insulating portions in which recesses conductive bars are formed which are in contact at the ends thereof with surface wirings provided on the two faces of the supporting plate, comprising the steps of forming said annular recesses on one side of a metal plate, each for receiving one of the ferromagnetic annular cores, each of said annular recesses including a group of conductive bars having their ends extending slightly above the surface of said one side of said metal plate, forming a plurality of groove-shaped recesses on said one side of said metal plate of greater depth than the annular recesses and circumscribing areas of connections between said bars for forming adjacent groups of said metal plate parts, placing the annular cores in the respective annular recesses, all recesses being subsequently filled with an insulating material so that on said side an insulating layer extends across said annular cores and said metal plate parts with the exception of said ends of said bars, printing on said layer wiring electrically connecting said ends, and removing the metal on the second side of said composite supporting plate to a depth such that the said circumscribed metal plate parts are electrically separated from each other with the exception of a conductive portion forming the other surface wiring.

2. A method as claimed in claim 1 wherein the recesses are formed by etching.

3. A method as claimed in claim 1 the recesses are formed by compression an extrusion of the metal.

4. A method as claimed in claim I wherein on the second side of the plate the metal is removed by etching.

5. A method as claimed in claim 1 wherein on the second side of the plate the metal is removed by grinding.

6. A memory matrix comprising ferromagnetic annular cores arranged in recesses of a composite support plate having metal plate parts electrically isolated from each other by insulating parts, inside each of which recesses a group of conductive bars are positioned to pass through said recess and extending therefrom said bars being in contact at the ends thereof with surface wiring on both sides of the supporting plate, said surface wiring formed on one side of said supporting plate by said metal plate parts integral with said bars, said surface including nonrecessed portions of said supporting plate extending up to the other side of said plate, the recesses between the metal plate parts being filled with insulating material. 

1. A method of manufacturing a memory matrix having ferromagnetic annular cores arranged in annular recesses of a composite supporting plate including metal plate parts and insulating portions in which recesses conductive bars are formed which are in contact at the ends thereof with surface wirings provided on the two faces of the supporting plate, comprising the steps of forming said annular recesses on one side of a metal plate, each for receiving one of the ferromagnetic annular cores, each of said annular recesses including a group of conductive bars having their ends extending slightly above the surface of said one side of said metal plate, forming a plurality of grooveshaped recesses on said one side of said metal plate of greater depth than the annular recesses and circumscribing areas of connections between said bars for forming adjacent groups of said metal plate parts, placing the annular cores in the respective annular recesses, all recesses being subsequently filled with an insulating material so that on said side an insulating layer extends across said annular cores and said metal plate parts with the exception of said ends of said bars, printing on said layer wiring electrically connecting said ends, and removing the metal on the second side of said composite supporting plate to a depth such that the said circumscribed metal plate parts are electrically separated from each other with the exception of a conductive portion forming the other surface wiring.
 2. A method as claimed in claim 1 wherein the recesses are formed by etching.
 3. A method as claimed in claim 1 the recesses are formed by compression an extrusion of the metal.
 4. A method as claimed in claim 1 wherein on the second side of the plate the metal is removed by etching.
 5. A method as claimed in claim 1 wherein on the second side of the plate the metal is removed by grinding.
 6. A memory matrix comprising ferromagnetic annular cores arranged in recesses of a composite support plate having metal plate parts electrically isolated from each other by insulating parts, inside each of which recesses a group of conductive bars are positioned to pass through said recess and extending therefrom said bars being in contact at the ends thereof with surface wiring on both sides of the supporting plate, said surface wiring formed on one side of said supporting plate by said metal plate parts integral with said bars, said surface including nonrecessed portions of said supporting plate extending up to the other side of said plate, the recesses between the metal plate parts being filled with insulating material. 